Coach Lynn Howells is deliberately keeping his side under wraps until two hours before kick-off, deterring Quins' Welsh ``spies'' Huw Harries and Gareth Llewellyn. Cardiff will win Pool Five should they beat the Londoners, and could even secure a home quarter-final if Welsh rivals Neath do them a favour by defeating Northampton later today.

Since being held 32-32 when Quins travelled to Wales in November, then crashing 46-13 in Montferrand, Cardiff have reeled off three successive group victories. It has taken them top of the pile, and Howells knows what is at stake this weekend.

``When Quins came down to us two months ago, they knew our team early and adapted their game accordingly to take account of players we had on the field,'' he said.

``It's a case of keeping them guessing this time. Huw Harries and Gareth Llewellyn know our players pretty well, so we don't want to give them any tactical advantage.''

Quins, courtesy of two losses against Italian champions Treviso, have already been eliminated.

The same effectively goes for Pool 4 opponents Saracens and Colomiers, who meet in Watford tomorrow, both sides having suffered at the hands of runaway group leaders Munster. Montferrand, meanwhile, should secure a best runners-up spot with victory over Treviso in France. If that happens, then they would go one better and win their qualifying pool as long as Quins see off Cardiff